1. Field of the Invention
The present invention relates to a semiconductor device and a method of manufacturing the same and, particularly, to a semiconductor device having a contact structure and a method of manufacturing the same.
2. Description of the Prior Art
A typical example of a conventional contact structure of a semiconductor device has been manufactured through the process steps mentioned below:
First, a diffusion region is formed in one of the major surfaces of a semiconductor substrate, then, an interlayer insulating film is formed over the entire major surface. Thereafter, a contact hole is formed in the interlayer insulating film to expose the diffusion region. Then, an aluminum wiring is formed on the interlayer insulating film with masking at least a sidewall of the contact hole and the exposed diffusion region.
In general, a passivation film is formed on the surface of the semiconductor element after the formation of the aluminum wiring. The passivation film is required to have a thickness at least equal to a certain constant thickness, e.g., 1 .mu.m, which is necessary to achieve a desired function of the passivation film. However, with the passivation structure in the conventional contact portion mentioned above, the thickness of the passivation film on an inner wall of the contact hole becomes smaller than that on other portion because formation of the passivation film on a shoulder portion of the contact hole starts earlier in its forming step than formation of the passivation film in the interior of the contact hole.
Therefore, in the conventional manufacturing method of semiconductor device, the function of the passivation film in the contact portion is not enough, resulting in degradation of reliability of the semiconductor device due to corrosion of the aluminum wiring, etc.